{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T01:55:10Z","timestamp":1775008510275,"version":"3.50.1"},"update-to":[{"DOI":"10.12688\/f1000research.52799.1","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2025,1,17]],"date-time":"2025-01-17T00:00:00Z","timestamp":1737072000000}}],"reference-count":22,"publisher":"F1000 Research Ltd","license":[{"start":{"date-parts":[[2025,1,17]],"date-time":"2025-01-17T00:00:00Z","timestamp":1737072000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010269","name":"Wellcome Trust","doi-asserted-by":"publisher","award":["OxTREC"],"award-info":[{"award-number":["OxTREC"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100010269","name":"Wellcome Trust","doi-asserted-by":"publisher","award":["49-12"],"award-info":[{"award-number":["49-12"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["f1000research.com"],"crossmark-restriction":false},"short-container-title":["F1000Res"],"abstract":"<ns3:p>\n                    Introduction Recent reports indicate the emergence of community-acquired pneumonia associated with K64-\n                    <ns3:italic>Klebsiella pneumoniae (K. pneumoniae)<\/ns3:italic>\n                    . Here, we identify the capsular types and sequence type of invasive and commensal\n                    <ns3:italic>K. pneumoniae<\/ns3:italic>\n                    isolates from Vietnam. Methods We included 93\n                    <ns3:italic>K. pneumoniae<\/ns3:italic>\n                    isolates from patients hospitalized at the National Hospital for Tropical Diseases, Hanoi between 2007 and 2011; and 110 commensal isolates from throat swabs from healthy volunteers living in rural and urban Hanoi in 2012. We determined sequence types (STs) by multi-locus sequence typing (MLST) and capsule typing for seven K types by PCR. Antibiotic susceptibility testing was performed using disk diffusion. Results The most common detected capsule types were K1 (39\/203, 19.2%, mainly ST23) and K2 (31\/203, 15.3%, multiple STs: ST65, ST86, ST380). We found significantly more K2 isolates among invasive in comparison to commensal isolates (22.6% vs 9%, p = 0.01) but no significant difference was observed between invasive and commensal K1 isolates (14.5% vs 24.7%, p = 0.075). K64 with varying sequence types were predominantly seen among invasive\n                    <ns3:italic>K. pneumoniae<\/ns3:italic>\n                    (8 vs. 3) and were isolated from sepsis and meningitis patients. Among K64 isolates, one was carbapenem-resistant with ST799. Conclusion Our study confirms that capsule type K64\n                    <ns3:italic>K. pneumoniae<\/ns3:italic>\n                    is associated with community-acquired invasive infections in Vietnam. Research is needed to unravel the mechanisms of virulence of capsule type K64 in both community and hospital settings.\n                  <\/ns3:p>","DOI":"10.12688\/f1000research.52799.2","type":"journal-article","created":{"date-parts":[[2025,1,17]],"date-time":"2025-01-17T12:15:08Z","timestamp":1737116108000},"page":"454","update-policy":"https:\/\/doi.org\/10.12688\/f1000research.crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Klebsiella pneumoniae with capsule type K64 is overrepresented among invasive disease in Vietnam"],"prefix":"10.12688","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6870-4096","authenticated-orcid":false,"given":"Bich","family":"Vu Thi Ngoc","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sylvain","family":"Brisse","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Trinh","family":"Dao Tuyet","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dung","family":"Vu Tien Viet","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kathryn E","family":"Holt","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Trung","family":"Nguyen Vu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huong","family":"Tran Thi Kieu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Diep","family":"Nguyen Thi Ngoc","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9807-1821","authenticated-orcid":false,"given":"H Rogier","family":"van Doorn","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heiman F L","family":"Wertheim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"2560","published-online":{"date-parts":[[2025,1,17]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"326-37","DOI":"10.1093\/trstmh\/tru058","article-title":"The bacterial aetiology of adult community-acquired pneumonia in Asia: a systematic review.","volume":"108","author":"L Peto","year":"2014 Jun","journal-title":"Trans R Soc Trop Med Hyg."},{"key":"ref2","doi-asserted-by":"publisher","first-page":"79","DOI":"10.1186\/s13054-019-2371-3","article-title":"Multidrug Resistant Gram-Negative Bacteria in Community-Acquired Pneumonia.","volume":"23","author":"C Cill\u00f3niz","year":"2019","journal-title":"Crit Care."},{"key":"ref20","doi-asserted-by":"publisher","first-page":"1111-23","DOI":"10.1080\/21505594.2017.1317412","article-title":"Hypervirulence and hypermucoviscosity: Two different but complementary Klebsiella spp. 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Palma","year":"2024","journal-title":"bioRxiv."}],"container-title":["F1000Research"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/f1000research.com\/articles\/10-454\/v2\/xml","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/f1000research.com\/articles\/10-454\/v2\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/f1000research.com\/articles\/10-454\/v2\/iparadigms","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,9]],"date-time":"2025-08-09T09:50:11Z","timestamp":1754733011000},"score":1,"resource":{"primary":{"URL":"https:\/\/f1000research.com\/articles\/10-454\/v2"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,1,17]]},"references-count":22,"URL":"https:\/\/doi.org\/10.12688\/f1000research.52799.2","relation":{"has-version":[{"id-type":"doi","id":"10.12688\/f1000research.52799.1","asserted-by":"subject"}],"has-review":[{"id-type":"doi","id":"10.5256\/f1000research.176630.r393103","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.176630.r360165","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.176630.r383866","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.176630.r393103","asserted-by":"object"},{"id-type":"doi","id":"10.5256\/f1000research.176630.r383866","asserted-by":"object"},{"id-type":"doi","id":"10.5256\/f1000research.176630.r360165","asserted-by":"object"}]},"ISSN":["2046-1402"],"issn-type":[{"value":"2046-1402","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,1,17]]},"assertion":[{"value":"Indexed","URL":"https:\/\/f1000research.com\/articles\/10-454\/v2#article-reports","order":0,"name":"referee-status","label":"Referee status","group":{"name":"current-referee-status","label":"Current Referee Status"}},{"value":"10.5256\/f1000research.56121.r93803, John L. Kiley, Brooke Army Medical Center, San Antonio, TX, 12 Oct 2021, version 1, 2 approved with reservations","URL":"https:\/\/f1000research.com\/articles\/10-454\/v1#referee-response-93803","order":0,"name":"referee-response-93803","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"<b>Bich Vu Thi Ngoc<\/b>; \n<i>Posted: 04 Jan 2025<\/i>; We would like to thank reviewer for your valuable comments. We have addressed all the reviewers\u2019 comments in the revised manuscript, including with additional information, and responded in the point-to-point rebuttal below. We hope our revisions are adequate and make our manuscript clear and publishable. \n<b>Reviewer 1<\/b> This paper describes the epidemiology of K64 \n<i>Klebsiella pneumoniae<\/i> isolates with a particular focus on K64 from a hospital in Vietnam. \n<b>Comment 1<\/b>: Introduction &quot;...but K64 capsular have rarely been described in healthy carriers.&quot; in the introductory paragraph reads a bit unclearly. \n<b>&nbsp;Response<\/b>:&nbsp; Thank you very much for your comment. We have now revised the sentence in the updated version as below: \u201c\u2026but carriage of K64 \n<i>K. pneumoniae <\/i>in healthy persons has rarely been described.\u201d \n<b>Comment 2: <\/b> Adding a bit more about the importance of K64 and the differences between classic and hypervirulent types of Klebsiella spp. (as well as how capsules might play a role in this) would better situate the authors' opening argument as to why they are performing this current study.&nbsp; \n<b>Response:<\/b> Thank you very much for your recommendation. We have now included the following sentences in the introduction of the manuscript: \n<i>K pneumoniae<\/i> is classified across two main virulence phenotypes, classical (cKp) and hypervirulent (hvKp). Most \n<i>K. pneumoniae<\/i> are associated with uncomplicated community acquired infections and nocosomial infections. However, hvKp results in more severe community \u2013 acquired infections with manifestations such as pyogenic liver abscess, meningitis, endophthalmitis, and necrotizing fasciitis. The polysaccharide capsule is perhaps the most well-known virulence factor of \n<i>K. pneumoniae<\/i>, including for the hvKp phenotype. The capsule surrounding \n<i>K. pneumoniae<\/i> cells can be divided into at least 79 capsular types (K1 to K79), among which K1, K2, and K64 are common serotypes of the MDR-hvKp group, which is commonly found in Asia. \n<b>Comment 3:<\/b> Methods &quot;302 \n<i>K. pneumoniae<\/i> were isolated...&quot; are these all isolates from the hospital during this time period? \n<b>Response: <\/b> Thank you very much for your question. The total number of isolates from the hospital during this time was 589 isolates; however, because this was a retrospective study, we performed re-culture, and 332\/589 isolates were recovered. Of those, 30 isolates had no associated clinical metadata, and were excluded from the study. We now have clarified this in the manuscript as below: \u201cFrom a total of 589 \n<i>K. pneumoniae<\/i> that were isolated from patients hospitalized at the National Hospital of Tropical Diseases between 2007 and 2011, 332 isolates were recovered after re-cultivation. Of those, 30 isolates with lacking clinical metadata were excluded, leaving the remaining 302 isolates for downstream analysis.\u201d \n<b>Comment 4:<\/b> Results I note that ESBL production was determined in Table 2 - please clarify how you determined this in the methods. \n<b>Response: <\/b> Thank you very much for your comment. We have added the information into the updated version as below: \u201cA phenotypic confirmatory double-disk test was performed for confirmation of ESBL production using CTX (30 mg) and CAZ (30 mg) disks alone and in combination with CA (10 mg) (Mast Diagnostic a GmbH, Reinfeld, Germany).\u201d \n<b>Comment 5:<\/b> Discussion and conclusion I think some discussion about the small numbers of K64 isolates would also be helpful in the limitations of the paper.&nbsp; The second paragraph starts off by suggesting K64 has &quot;been little reported so far,&quot; but I think the data from China would argue against this. \n<b>Response:<\/b> Thank you for your recommendation. We agree that data from China would argue against our statement in the second paragraph starts off by suggesting K64 has &quot;been little reported so far,&quot;. We now have revised the sentence as below: \u201cThe capsular type K64 has been reported worldwide, especially from clinical settings in Asia, Europe, and North America and is one of the K types associated with hypervirulent strains, that have shown simultaneous expression of virulence and carbapenem-resistance genes, posing a treatment challenge.\u201d  Regarding the small numbers of K64 isolates in our study, we have added into the limitation: \u201cIn this study, the relatively small number of K64 isolates provided only limited data about the serotype's convergent virulence and carbapenem resistance. Also, we lack the whole genome sequence data of these K64 isolates for further understanding of the molecular basis of hypervirulence and the phylogenetic positioning of this rare ST within the genomic taxonomy of \n<i>K. pneumoniae<\/i>. However, our results led support to the hypothesis that K64 is associated with severe invasive community acquired \n<i>K. pneumoniae<\/i> infections, including sepsis and meningitis. In addition, here, only seven capsule types were selected to investigate the diversity of \n<i>K. pneumoniae<\/i> isolates. We recognize that this is one of the limitations of our study. Further studies are needed to unravel the mechanisms of virulence of capsule type K64 in \n<i>K. pneumoniae<\/i>.\u201d","URL":"https:\/\/f1000research.com\/articles\/10-454\/v2#referee-comment-13076","order":1,"name":"referee-comment-13076","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.5256\/f1000research.176630.r360165, Frank R. DeLeo, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, 28 Jan 2025, version 2, indexed","URL":"https:\/\/f1000research.com\/articles\/10-454\/v2#referee-response-360165","order":2,"name":"referee-response-360165","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.5256\/f1000research.176630.r383866, Ning Dong, Zhejiang University School of Medicine, Hangzhou, 06 Jun 2025, version 2, indexed","URL":"https:\/\/f1000research.com\/articles\/10-454\/v2#referee-response-383866","order":3,"name":"referee-response-383866","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.5256\/f1000research.176630.r393103, Neris Garc\u00eda-Gonz\u00e1lez, Instituto de Biomedicina de Valencia (Ringgold ID: 54426), Valencia, Valencian Community, 09 Aug 2025, version 2, indexed","URL":"https:\/\/f1000research.com\/articles\/10-454\/v2#referee-response-393103","order":4,"name":"referee-response-393103","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Wellcome Trust OxTREC, 49-12. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.","order":5,"name":"grant-information","label":"Grant Information"},{"value":"This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.","order":0,"name":"copyright-info","label":"Copyright"}]}}